What is Cold fusion ?

he term "cold fusion" became popular in 1989 when two scientists (Martin Fleischmann and Stanley Pons) announced that they were able to achieve a cold fusion reaction - something previously thought impossible given scientific theory.

The initial euphoria over the achievement of turned to controversy when other scientists claimed they were unable to replicate the test results. This led to charges that the two scientists had either doctored their data or became embroiled in wishful thinking. The controversy, which was widely reported in scientific publications and the media, ended with both scientists in disgrace.

In the years since, however, various scientists have achieved cold fusion reactions using a variety of approaches. Scientists at UCLA, for example, used a small lithium tantalite crystal (a pyroelectric substance that forms an electric charge when heated) placed within a hydrogen-filled chamber. When they warmed the crystal (from -30 F to 45 F), a 100,000-volt electrical field formed across the small crystal. A metal wire placed near the crystal discharged the electrical charge at a single point - and the hydrogen atoms in the chamber started smacking into other hydrogen atoms. The scientists noted the creation of helium nuclei, the release of high-energy radiation and free neutrons - all signs of fusion reaction. Similar results, using other methods, have been reported at various scientific installations.

Unfortunately, cold fusion as a cheap, reliable energy source is still currently unlikely. While the above experiments appear to prove the feasibility of fusion reactions without the need for gigantic equipment or massive amounts of energy, power output generated is still way below the amount of actual energy used.

Most physicists can probably remember where they were when they first heard of Stanley Pons and Martin Fleischmann. On 23 March 1989 the two electrochemists grabbed the world's attention by announcing at a press conference in Salt Lake City, Utah, that they had observed controlled nuclear fusion in a glass jar. The excess heat measured in the experiment offered the promise of a new power source for the planet, as well as huge financial rewards.

However, it is clear that world energy production has not been affected in any way by cold fusion. No experiment has so far convinced the sceptics that cold fusion is real, and most of the big funding sources, which threw money at quick experiments in the early days of cold fusion, have pulled out. Retired particle physicist Douglas Morrison, one of the more persistent critics of cold fusion, says that after ten years there is "less science, fewer scientists, fewer funds, [although there are] more potential investors".

But cold fusion is not dead and buried. A dedicated circle of enthusiasts has kept the flame alive to varying degrees, carrying out jury-rigged experiments in garages and basements, and one or two more conventional institutions still have an interest. Although governments such as those of the US and Japan have officially pulled out, the cold-fusion faithful say that several government agencies are still giving money to the field, including the US Department of Defense. And the Italian and French governments are still supporting research in a small number of labs, according to one cold-fusion insider.

Fusion on a lab bench

A couple of palladium electrodes in heavy water and any high-school kid could do it, it was said. Pons, in the chemistry department at the University of Utah, and his mentor Martin Fleischmann, of Southampton University in the UK, claimed at the press conference in 1989 that they had fused deuterium nuclei using routine electrochemical techniques on their lab bench. This was a huge claim to make - nuclear fusion had been thought possible only at temperatures in excess of a million degrees, when nuclei could overcome Coulomb repulsion. The only cold fusion that had been detected until then was the kind mediated by muons, seen in acceleratorexperiments in the 1950s, and then only at minuscule rates.

Indeed, questions were soon raised about the reliability of Pons and Fleischmann's nuclear measurements, given their lack of experience in quantitative isotope analysis. Soon after they announced their findings, laboratories around the world tried but failed to replicate their results. In the rush to duplicate the cold-fusion results, chemists began attempting nuclear physics, and physicists tried to be electrochemists. In the months that followed many labs rushed into experiments, and hastily announced confirmation of cold fusion before they had carried out adequate controls. They then had to make equally speedy retractions when the experiments did not succeed.

Eventually, a group at the Massachusetts Institute of Technology (MIT) found serious flaws in the gamma-ray spectra that Pons and Fleischmann offered as proof. This was to be the death knell, and the final nails in the coffin of cold fusion were hammered in by a US Department of Energy panel that concluded in October 1989 that there was nothing to cold fusion. This in turn spawned bitter accusations that hot-fusion physicists and particle physicists were out to get the cold-fusion community.

The University of Utah continued to press forward with a cold-fusion research institute, but that lab was eventually disbanded in 1991 when it failed to replicate the earlier results. Pons and Fleischmann departed in 1992 for the south of France, where the Technova company, a subsidiary of the Toyota car company, funded a new laboratory called IMRA. As time went on, all but the diehards gave up, and the major reputable labs lost interest and dropped out of the experimental game.

Work on cold fusion continued in several countries, notably Japan, and this was often cited by cold-fusion believers as evidence that that US would be left in the dust when the new world energy order finally dawned. But in 1997 Japan's government finally gave up. And in 1998 IMRA was closed, having spent something like £12m on cold-fusion work. Then in March 1998 something of a milestone may have been reached. The University of Utah finally gave up its struggle to obtain worldwide patents on Pons and Fleischmann's work, having been legally bound to pursue patents until last year. The rights now revert to Pons and Fleischmann themselves, should they choose to continue the pursuit of patents.

Sporadic reports have continued to trickle in from various small research efforts, but in each case the results have proved erratic or impossible for other groups to replicate. It appeared to be a classic case of what the Nobel chemist Irving Langmuir called "pathological science", in which the results are always near the limit of detectability and the proponents always have an ad hoc answer as to why. Yet the defenders of cold fusion have soldiered on, a number of them merging with a network of conspiracy theorists, psychic spoon-benders, UFO enthusiasts and believers in other exotic physical phenomena outside the ken of science.

Cold fusion: the culture

Cold fusion may have been written off by the scientific community at large, but it has entered cultural consciousness in interesting ways. Hollywood embraced the subject in 1997 in the action movie The Saint. Just before the female physicist and the leading man fall into bed for the happy ending, a mythical post-Yeltsin Russia is saved from demented Moscow mafia types by limitless energy generated by electrodes in a bottle. Pons and Fleischmann, though only invoked in the early scenes of the film, stand vindicated. Another film called Breaking Symmetry has just been produced by former MIT materials science professor Keith Johnson. Here, the evil hot-fusion scientists, attempting to protect their millions of tokamak research dollars, engage in various dirty tricks to squelch the discovery of real cold fusion at a fictional lab.

Cold fusion has even been turned into a game. Trevor Pinch of the Science and Technology Studies Department at Cornell University created a hypertext game in which you pretend to be an experimenter trying to replicate the Pons and Fleischmann experiment. Depending on what choices you make, you end up either with your reputation intact or a career in tatters. Cold fusion lives on in other ways too: there is a software product called Cold Fusion for hooking databases to Web sites, a rock band with that name in the US, and a sports equipment company that makes snowboards.